Dietary digestible lysine in free-range broiler chickens during the growth phase

This experiment was conducted to determine the requirements of digestible lysine in male and female free-range broiler chickens (Redbro lineage) during the growth phase. Six hundred and thirty broiler chickens were allocated in 30 pens with access to the pasture area. The experimental design was completely randomized in a 5x2 (lysine and gender) factorial arrangement with 3 repetitions with 21 chickens each. The levels of digestible lysine evaluated were: 7.07, 8.07, 9.07, 10.07 and 11.07g/kg. The performance traits evaluated were lysine intake, feed intake, weight gain and feed conversion ratio. An interaction effect (P<0.05) was observed between dietary lysine level and gender for body weight gain. There was an effect (P<0.01) of the levels of lysine on lysine intake, body weight gain and feed conversion ratio. It was found that all the variables were affected (P<0.05) for the gender of chickens. We recommended 10.08 and 9.49 g of digestible lysine/kg diet, corresponding to the estimated intake of 21 and 20g of lysine, for males and females, respectively, for better body weight gain of chickens. For better feed conversion ratio, the recommendation is of 9.61 g of lysine/kg of diets, for chickens of both genders, corresponding to the estimated intake of 20g of lysine.